JWT generation

I am trying to generate a JWT using python. I followed the given example in the documentation, but I always get error 400. 

I am using the following code:

# BASE URL for Zephyr for Jira Cloud
BASE_URL = 'https://prod-api.zephyr4jiracloud.com/connect'

# RELATIVE PATH for token generation and make request to api
RELATIVE_PATH = '/public/rest/api/1.0/cycle'

# CANONICAL PATH (Http Method & Relative Path & Query String)
CANONICAL_PATH = 'POST&'+RELATIVE_PATH+'&'


# TOKEN HEADER: to generate jwt token
payload_token = {
            'sub': ACCOUNT_ID,
            'qsh': hashlib.sha256(CANONICAL_PATH.encode('utf-8')).hexdigest(),
            'iss': ACCESS_KEY,
            'exp': int(time.time())+JWT_EXPIRE,
            'iat': int(time.time())
        }


# GENERATE TOKEN
token = jwt.encode(payload_token, SECRET_KEY, algorithm='HS256').strip()


headers = {
  'Content-Type': 'application/json',
  'Authorization': 'JWT '+token,
  'zapiAccessKey': ACCESS_KEY
}

# REQUEST PAYLOAD: to create cycle
cycle = {
            'name': 'Sample Cycle',
            'projectId':  '10200',
            'versionId': '5.X'
        }

raw_result = requests.post(BASE_URL + RELATIVE_PATH, headers=headers, json=cycle)

Could anyone tell me what I'm doing wrong?